1. Field of the Invention
The present invention relates to a side impact air bag system which is inflated between a driver or a passenger seated in a vehicle and an inner wall of a vehicle compartment for absorbing a collision energy when a collision impact is applied externally to a side of the vehicle.
2. Prior Art
In a practically used vehicle air bag system, an air bag is built in a steering wheel at a driver's seat side or an instrument panel at a passenger's seat side. If a collision occurs against a front end of a vehicle, the air bag is momentarily inflated for absorbing a forward inertial force applied to a passenger (including a driver), thereby preventing a secondary collision of the passenger against the steering wheel, the instrument panel or the like. Further, a side impact air bag system is developed in which an air bag is built in an inner wall of a vehicle compartment, an inner wall of a door, a seat back or the like. When a collision occurs against a side of the vehicle, the air bag is momentarily inflated for preventing a secondary collision of an upper half of body the passenger against the inner wall of the door or the like.
When a collision force is applied externally to a side of the vehicle, a collided side wall of the vehicle is moved toward a center of the vehicle compartment at an opposite side with respect to the point of collision, and a seat cushion is moved via a side sill and a floor to the center of the vehicle compartment. Since the passenger is not fixed to the seat cushion, the passenger tends to stay due to inertia. Therefore, there is a possibility of the secondary collision between the inner wall of the vehicle compartment moving toward the center and the upper half body of the passenger. The aforementioned side impact air bag system is for the safety of the passenger in case of such vehicle side collision.
FIGS. 13(a) and 13(b) show a seat mounted side air bag system. In FIGS. 13(a) and 13(b), seat S has a seat cushion 1 and a seat back 2. Inside a side support 3 at a door side of the seat back 2, an air bag module 7 including an inflator 5 and an air bag 6, disposed behind a cushion pad 4, are contained. A portion where the air bag 6 is inflated from the air bag module 7 is covered with the cushion pad 4. Further, a covering 8 for covering a surface of the seat back 2 has a front cover 8a and a side cover 8b sewn or closed together at corners with a seam 8c.
When an impact applied to the side of the vehicle is detected by a sensor (not shown) for detecting an impact resulting from a side collision against the vehicle, an operation command is transmitted to the inflator 5, and rare gas or another inflating gas is momentarily blown from the inflator 5 into the air bag 6. The air bag 6 is inflated to tear the cushion pad 4 and the seam 8c and deployed outwardly.
As shown in FIGS. 14 and 15, the air bag 6 is divided by a partition 9 into a lower chamber 6a and an upper chamber 6b. The partition 9 is provided with a vent or a communication hole 9a. Gas blown from the inflator 5 first flows directly into the lower chamber 6a, and successively via the communication hole 9a into the upper chamber 6b. Therefore, the lower chamber 6a of the air bag 6 is inflated between a torso 10a of a passenger 10 and an inner wall of a vehicle compartment, and the upper chamber 6b is successively inflated between a head 10b of the passenger 10 and the inner wall of the vehicle compartment, thereby protecting the upper half of the passenger 10 (the torso 10a and the head 10b) from a secondary collision against the inner wall of the vehicle compartment. The air bag system having the aforementioned constitution is disclosed, for example, in the publications of Japanese Patent Application laid-open Nos. Hei 06-227348, 08-067228 and the like.
In the seat mounted side air bag device shown in FIG. 13, the air bag 6 is divided by the partition 9 into the lower chamber 6a and the upper chamber 6b. Gas blown from the inflator 5 flows directly into the lower chamber 6a, and successively via the communication hole 9a into the upper chamber 6b. The lower chamber 6a of the air bag 6 is deployed between the torso 10a of the passenger 10 and the inner wall of the vehicle compartment, and successively the upper chamber 6b is deployed between the head 10b of the passenger 10 and the inner wall of the vehicle compartment.
In this case, when inflating gas flows via the communication hole 9a into the upper chamber 6b to inflate the upper chamber 6b, as shown in FIG. 16(a), the upper chamber 6b interferes with a seat belt X. As a result, as shown by a dotted line in FIG. 16(a), a cavity a is formed in the upper chamber 6b and the upper chamber 6b is disadvantageously obstructed by the seat belt X from being completely inflated.
In another constitution shown in FIG. 16(b), the communication hole 9a is provided in a vehicle front side of the partition 9 of the air bag 6. The gas blown from the inflator 5 is reflected by a point b on an inner wall of the air bag 6, so that the gas flows toward a vehicle rear side of the upper chamber 6b. Even in this constitution, when the upper chamber 6b is inflated toward the vehicle rear side of the seat belt X, the upper chamber 6b also interferes with the seat belt X. As shown by a dotted line, a cavity c is formed in the vehicle front side of the upper chamber 6b, and the upper chamber 6b is obstructed by the seat belt X from being completely inflated.
In either of the aforementioned constitutions, the upper chamber 6b of the air bag 6 is obstructed from being completely deployed between the head of the passenger and the inner wall of the vehicle compartment, and a collision energy applied to the head is disadvantageously difficult to be sufficiently absorbed.